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Gate implicit mutable by-reference bindings behind mut ref

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This commit is contained in:
Jules Bertholet 2024-05-15 16:55:54 -04:00
parent eb91f3b051
commit 0746577fa2
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GPG key ID: 32034DAFC38C1BFC
11 changed files with 61 additions and 65 deletions
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2
compiler/rustc_feature/src/removed.rs
View file

@ -128,6 +128,8 @@ macro_rules! declare_features {
/// Allows the use of type alias impl trait in function return positions
(removed, min_type_alias_impl_trait, "1.56.0", Some(63063),
Some("removed in favor of full type_alias_impl_trait")),
/// Make `mut` not reset the binding mode on edition >= 2024.
(removed, mut_preserve_binding_mode_2024, "1.79.0", Some(123076), Some("superseded by `ref_pat_eat_one_layer_2024`")),
(removed, needs_allocator, "1.4.0", Some(27389),
Some("subsumed by `#![feature(allocator_internals)]`")),
/// Allows use of unary negate on unsigned integers, e.g., -e for e: u8

2
compiler/rustc_feature/src/unstable.rs
View file

@ -527,8 +527,6 @@ pub fn internal(&self, feature: Symbol) -> bool {
(unstable, more_qualified_paths, "1.54.0", Some(86935)),
/// Allows the `#[must_not_suspend]` attribute.
(unstable, must_not_suspend, "1.57.0", Some(83310)),
/// Make `mut` not reset the binding mode on edition >= 2024.
(incomplete, mut_preserve_binding_mode_2024, "1.79.0", Some(123076)),
/// Allows `mut ref` and `mut ref mut` identifier patterns.
(incomplete, mut_ref, "1.79.0", Some(123076)),
/// Allows using `#[naked]` on functions.

34
compiler/rustc_hir_typeck/src/pat.rs
View file

@ -12,7 +12,7 @@
use rustc_middle::mir::interpret::ErrorHandled;
use rustc_middle::ty::{self, Ty, TypeVisitableExt};
use rustc_middle::{bug, span_bug};
use rustc_session::lint::builtin::NON_EXHAUSTIVE_OMITTED_PATTERNS;
use rustc_session::{lint::builtin::NON_EXHAUSTIVE_OMITTED_PATTERNS, parse::feature_err};
use rustc_span::edit_distance::find_best_match_for_name;
use rustc_span::hygiene::DesugaringKind;
use rustc_span::source_map::Spanned;
@ -669,17 +669,27 @@ fn check_pat_ident(
// Determine the binding mode...
let bm = match user_bind_annot {
// `mut` resets binding mode on edition <= 2021
BindingMode(ByRef::No, Mutability::Mut)
if !(pat.span.at_least_rust_2024()
&& self.tcx.features().mut_preserve_binding_mode_2024)
&& matches!(def_br, ByRef::Yes(_)) =>
{
self.typeck_results
.borrow_mut()
.rust_2024_migration_desugared_pats_mut()
.insert(pat_info.top_info.hir_id);
BindingMode(ByRef::No, Mutability::Mut)
BindingMode(ByRef::No, Mutability::Mut) if matches!(def_br, ByRef::Yes(_)) => {
if pat.span.at_least_rust_2024() && self.tcx.features().ref_pat_eat_one_layer_2024 {
if !self.tcx.features().mut_ref {
feature_err(
&self.tcx.sess,
sym::mut_ref,
pat.span.until(ident.span),
"binding cannot be both mutable and by-reference",
)
.emit();
}
BindingMode(def_br, Mutability::Mut)
} else {
// `mut` resets binding mode on edition <= 2021
self.typeck_results
.borrow_mut()
.rust_2024_migration_desugared_pats_mut()
.insert(pat_info.top_info.hir_id);
BindingMode(ByRef::No, Mutability::Mut)
}
}
BindingMode(ByRef::No, mutbl) => BindingMode(def_br, mutbl),
BindingMode(ByRef::Yes(_), _) => user_bind_annot,

10
tests/ui/match/ref_pat_eat_one_layer_2024/ref_pat_eat_one_layer_2024_fail.rs
View file

@ -49,4 +49,14 @@ pub fn main() {
let &mut &mut &mut &mut _ = &mut &&&&mut &&&mut &mut 0;
//~^ ERROR: mismatched types
struct Foo(u8);
let Foo(mut a) = &Foo(0);
//~^ ERROR: binding cannot be both mutable and by-reference
a = &42;
let Foo(mut a) = &mut Foo(0);
//~^ ERROR: binding cannot be both mutable and by-reference
a = &mut 42;
}

25
tests/ui/match/ref_pat_eat_one_layer_2024/ref_pat_eat_one_layer_2024_fail.stderr
View file

@ -152,6 +152,27 @@ LL | let &mut &mut &mut &mut _ = &mut &&&&mut &&&mut &mut 0;
= note: expected reference `&&&&mut &&&mut &mut {integer}`
found mutable reference `&mut _`
error: aborting due to 14 previous errors
error[E0658]: binding cannot be both mutable and by-reference
--> $DIR/ref_pat_eat_one_layer_2024_fail.rs:55:13
|
LL | let Foo(mut a) = &Foo(0);
| ^^^^
|
= note: see issue #123076 <https://github.com/rust-lang/rust/issues/123076> for more information
= help: add `#![feature(mut_ref)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
For more information about this error, try `rustc --explain E0308`.
error[E0658]: binding cannot be both mutable and by-reference
--> $DIR/ref_pat_eat_one_layer_2024_fail.rs:59:13
|
LL | let Foo(mut a) = &mut Foo(0);
| ^^^^
|
= note: see issue #123076 <https://github.com/rust-lang/rust/issues/123076> for more information
= help: add `#![feature(mut_ref)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error: aborting due to 16 previous errors
Some errors have detailed explanations: E0308, E0658.
For more information about an error, try `rustc --explain E0308`.

14
tests/ui/pattern/feature-gate-mut_preserve_binding_mode_2024.rs
View file

@ -1,14 +0,0 @@
//@ edition: 2024
//@ compile-flags: -Zunstable-options
struct Foo(u8);
fn main() {
let Foo(mut a) = &Foo(0);
a = &42;
//~^ ERROR: mismatched types
let Foo(mut a) = &mut Foo(0);
a = &mut 42;
//~^ ERROR: mismatched types
}

31
tests/ui/pattern/feature-gate-mut_preserve_binding_mode_2024.stderr
View file

@ -1,31 +0,0 @@
error[E0308]: mismatched types
--> $DIR/feature-gate-mut_preserve_binding_mode_2024.rs:8:9
|
LL | let Foo(mut a) = &Foo(0);
| ----- expected due to the type of this binding
LL | a = &42;
| ^^^ expected `u8`, found `&{integer}`
|
help: consider removing the borrow
|
LL - a = &42;
LL + a = 42;
|
error[E0308]: mismatched types
--> $DIR/feature-gate-mut_preserve_binding_mode_2024.rs:12:9
|
LL | let Foo(mut a) = &mut Foo(0);
| ----- expected due to the type of this binding
LL | a = &mut 42;
| ^^^^^^^ expected `u8`, found `&mut {integer}`
|
help: consider removing the borrow
|
LL - a = &mut 42;
LL + a = 42;
|
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0308`.

2
tests/ui/pattern/match_ergonomics_2024.fixed
View file

@ -2,7 +2,7 @@
//@ run-rustfix
//@ rustfix-only-machine-applicable
//@ aux-build:match_ergonomics_2024_macros.rs
#![feature(mut_preserve_binding_mode_2024, ref_pat_eat_one_layer_2024)]
#![feature(mut_ref, ref_pat_eat_one_layer_2024)]
#![allow(incomplete_features, unused)]
#![deny(rust_2024_incompatible_pat)]

2
tests/ui/pattern/match_ergonomics_2024.rs
View file

@ -2,7 +2,7 @@
//@ run-rustfix
//@ rustfix-only-machine-applicable
//@ aux-build:match_ergonomics_2024_macros.rs
#![feature(mut_preserve_binding_mode_2024, ref_pat_eat_one_layer_2024)]
#![feature(mut_ref, ref_pat_eat_one_layer_2024)]
#![allow(incomplete_features, unused)]
#![deny(rust_2024_incompatible_pat)]

2
tests/ui/pattern/mut_preserve_binding_mode_2021.rs
View file

@ -1,6 +1,6 @@
//@ edition: 2021
//@ compile-flags: -Zunstable-options
#![feature(mut_preserve_binding_mode_2024)]
#![feature(ref_pat_eat_one_layer_2024)]
#![allow(incomplete_features)]
struct Foo(u8);

2
tests/ui/pattern/mut_preserve_binding_mode_2024.rs
View file

@ -1,7 +1,7 @@
//@ run-pass
//@ edition: 2024
//@ compile-flags: -Zunstable-options
#![feature(mut_preserve_binding_mode_2024)]
#![feature(mut_ref, ref_pat_eat_one_layer_2024)]
#![allow(incomplete_features, unused)]
struct Foo(u8);